Can you add the facility to enter the total cost of a fill up instead of the price per litre or gallon?

Like many on here I record my odometer reading on the receipt when I buy fuel. Unfortunately the oil company I normally use (Shell) does not record the price per litre on the receipt. So I have to use a calculator each time I enter the data on fuelly.

Everyone is very aware of the total they paid, but not always the price per litre or gallon. Surely this would be easy to implement, either as a user profile option, or as an either/or on the entry form?

As far as we know this is only a problem in the UK. I'm not sure why companies there don't put the price/litre on the receipt while they do in every other part of the world. Shell in the US always lists price/gallon on receipts.

Our mantra has always been: don't complicate the fuel-up form. But I think we will need to add total cost to work around this problem.